When blood comes into contact with foreign surfaces there is an activation of the coagulation and the inflammatory system. Although biomedical device technology has made progress, a surface that is completely biocompatible for long term use, has not been achieved. The clinical means to prevent thrombosis is still the co-administration of the anticoagulants, predominantly bolus heparin. STS is developing heparin-containing polymers (MEDI- COAT(TM)) for coating vascular catheters, to render them non-thrombogenic for extended periods. The Phase I proportion of this project will determine the basic extraction parameters of heparin, in vitro and in vivo, from MEDI-COAT anti- thrombogenic catheters. Radioactive heparin will allow for a direct measure of these parameters. Biochemical assays will be utilized to measure extracted heparin concentrations and anti-thrombogenic activity. Finally, an animal model will assess and measure the heparin extraction from catheters in vivo and the resultant anticoagulant activity. For Phase II portion of the project, it is anticipated that the changing coating parameters such as heparin concentration and heparin/polymer formulation, catheters can be developed with anti-thrombogenic activity for specified time durations of a few hours, a few days or for many months. PROPOSED COMMERCIAL APPLICATIONS: Medical devices and procedures that would benefit from anti-thrombogenic MEDI-COAT(TM) system include indwelling catheters, coronary-bypass oxygenators, coronary stents and hemodialysis equipment.